1. Technical Field
The present disclosure relates to a method of manufacturing a nonaqueous electrolyte secondary battery.
2. Description of Related Art
In a nonaqueous electrolyte secondary battery, in a case where the potential of a positive electrode active material (equivalent to the potential of a positive electrode) increases due to initial charging or the like, a solvent of a nonaqueous electrolytic solution is oxidized and decomposed on a surface of the positive electrode active material, and hydrogen ions produced by the oxidative decomposition may react with fluorine ions in the nonaqueous electrolytic solution to produce hydrofluoric acid (HF). Due to the action of the hydrofluoric acid, a transition metal is eluted from the positive electrode active material, and the performance of the battery may deteriorate.
On the other hand, Japanese Patent Application Publication No. 2014-103098 (JP 2014-103098 A) discloses a technique of adding lithium phosphate to a positive electrode mixture layer such that hydrofluoric acid produced as described above is caused to react with lithium phosphate (Li3PO4) to reduce the amount of the hydrofluoric acid and thereby to reduce the elution of a transition metal from a positive electrode active material. Specifically, in JP 2014-103098 A, a positive electrode mixture paste is prepared by kneading (stirring) a positive electrode active material, a conductive material, a neutral binder, lithium phosphate, and a solvent. The prepared positive electrode mixture paste is applied to a current collector member and is dried. As a result, a positive electrode that includes a positive electrode mixture layer containing lithium phosphate is prepared.